1. Field of the Invention
The present invention relates to a photoelectric conversion device.
2. Description of the Related Art
The miniaturization of a pixel (photoelectric conversion element) of a photoelectric conversion device has rapidly progressed owing to the spread of a small-sized light digital camera and a mobile phone with a camera function. Because an incident light into a photoelectric conversion element has decreased as the progress of the miniaturization, the improvement of the sensitivity of the photoelectric conversion element has been required. In order to improve the sensitivity, it has been examined to enlarge the area of the light receiving portion of a photoelectric conversion element to improve the aperture ratio thereof. However, if the area of the light receiving portion is enlarged, then the occurrence of color mixture, the so-called crosstalk, owing to the mixing of a light into an adjacent photoelectric conversion element becomes easy. In particular, in a metal oxide semiconductor (MOS) type photoelectric conversion device including a multilayered wiring structure, the distance from the uppermost surface of the multilayered wiring structure to the light receiving surface of a photoelectric conversion element becomes longer, and the crosstalk is easily generated. As a measure for the crosstalk, a structure of forming an air gap in an insulation layer disposed between metal wiring layers is disclosed in U.S. Pat. No. 7,012,240.